目的 探索猕猴桃多糖对前胃癌（MFC）细胞及其原位移植瘤细胞凋亡的分子机制。方法 采用MTT法检测猕猴桃多糖对MFC细胞增殖抑制率，Western blotting法检测MFC细胞Mcl-1、Bcl-2、Bak和Bcl-xl蛋白的表达；OB吻合胶粘贴法建立胃癌原位移植瘤模型，采用TUNEL法检测肿瘤组织中细胞凋亡情况，免疫组织化方法检测Bcl-2、Bax的表达情况。结果 MTT实验表明随着猕猴桃多糖质量浓度的增加对MFC细胞增殖的抑制作用增强，且随着作用时间的延长，其抑制作用增强；Western blotting实验表明猕猴桃多糖作用于MFC细胞24 h下调Mcl-1、Bcl-2、Bcl-xl蛋白的表达，上调Bak蛋白的表达；体内实验表明：与模型组比较，猕猴桃多糖中、高剂量组及5-氟尿嘧啶（5-Fu）阳性对照组中TUNEL检测细胞凋亡的平均阳性指数明显升高（P＜0.01）；各给药组均能够显著下调Bcl-2的表达、上调Bax的表达（P＜0.01）。结论 猕猴桃多糖能够诱导胃癌MFC细胞凋亡，下调MFC细胞Mcl-1、Bcl-2、Bcl-xl蛋白和上调Bax、Bak蛋白表达，提示猕猴桃多糖的抗肿瘤机制与其通过Bcl-2家族蛋白所参与的细胞凋亡途径有关。

Objective To explore the effect of Actinidia chinensis polysaccharide (ACP) on apoptosis of MFC cells and their orthotopic transplanted tumor of gastric cancer and the molecular mechanism. Methods MTT method was used to detect the inhibitory rate of ACP on MFC cell proliferation and the expression of Mcl-1, Bcl-2, Bak, and Bcl-xl protein was detected by Western blotting; The model of orthotopic transplanted tumor of gastric cancer was established with OB anastomosis adhesive stick method; Cell apoptosis in tumor tissue was detected by TUNEL method; The expression of Bcl-2 and Bax was detected by immunohistochemistry method. Results MTT results showed that with the increasing of ACP concentration, the inhibition of ACP on MFC cell proliferation became stronger and with the prolongation of time, the inhibition was increasing. Western blotting showed that ACP would downregulate the expression of Mcl-1, Bcl-2, and Bcl-xl protein and upregulate the expression of Bak protein when the MFC cells were treated for 24 h by ACP. The animal experiment showed that compared with the model group, the average positive indexes of ACP in mid- and high-dose ACP and 5-FU positive control groups in the detection of apoptosis by TUNEL were significantly increased (P < 0.01); Meanwhile, in all ACP groups the expression of Bcl-2 could be reduced and the expression of Bax was upregulated significantly (P < 0.01). Conclusion ACP could induce apoptosis of gastric cancer cells, downregulate the expression of Mcl-1, Bcl-2, and Bcl-xl protein, and upregulate the expression of Bak and Bax protein, prompting that the antitumor mechanism of ACP is related with the apoptosis pathway in which the Bcl-2 family proteins are involved.

国家自然科学基金资助项目（81273904）；浙江省自然科学基金资助项目（Y2100827）；浙江中医药大学校级重点课题资助项目（2010ZZ10）